This revision responds to Notice NOT-OD-09-058, Availability of Recovery Act Funds for Competitive Revision Applications. The parent grant to this revision longitudinally measures sleep and EEG changes across childhood and adolescence. One specific aim of the parent project is to establish maturational curves that will provide the baseline data needed for future studies of sleep EEG maturation in children with mental illness or developmental disorders. Our ongoing parent study has identified ages 11 to 16 years as a period of rapid sleep EEG maturation. We have interpreted the 66% decline in delta (1- 4 Hz) EEG power density over this age range as an indicator of an adolescent brain maturation driven by synaptic pruning. Studies of MRI-measured cortical thickness, also thought to be related to synaptic density, have found a developmental lag in subjects with attention deficit hyperactivity disorder (ADHD). The goal of this Revision application is to test the hypothesis that there is a similar lag in sleep EEG maturation. We will test this hypothesis by studying two age groups (mean age 10 years and mean age 14 years) of subjects diagnosed with ADHD. Although the parent grant measures the adolescent EEG changes longitudinally, the slow wave EEG decline can also be robustly detected in cross-sectional analysis;thus, cohorts in our baseline at mean age 14 years show significantly lower delta and theta power density than an independent 10 year old cohort. If children with ADHD have a developmental lag, we hypothesize that the difference in the EEG power density between ADHD groups over these ages will be significantly smaller. In addition to providing an initial test for a developmental lag in sleep electrophysiology in ADHD, the data we will obtain in this Revision should provide guidelines for future longitudinal investigations of sleep EEG maturation in ADHD. In addition, they will greatly expand the existing data base on computer-measured sleep EEG in this condition. PUBLIC HEALTH RELEVANCE: The human brain undergoes a major reorganization during adolescence. Mental illness may be associated with abnormalities in this reorganization. MRI studies show that children with ADHD have a developmental lag in cortical development. We will determine whether children with ADHD show a developmental lag in sleep EEG maturation. Either a positive or negative result will expand knowledge of the neurophysiology of this disorder. A positive result could be of diagnostic or prognostic value.